All-Australian defender Ash Brazill appears to have suffered a torn left ACL during Collingwood's match against Melbourne.
The star Pie was attempting to corral a Melbourne opponent when her knee gave way while changing direction.
Brazill, 30, is Collingwood's vice-captain and structurally one of its most important players, a rare type who can lock down an opponent as a key defender and burst away on the rebound.
"We're just waiting to see. All you guys would have seen her go down, so we're just waiting to hear back as to what that's all about," Collingwood coach Steve Symonds said.
"Hopefully fingers crossed and that, but it probably didn't look like what we wanted to see.
"We'll try and get [scans] done as quickly as we can, so we suspect that'll be tonight or tomorrow, but our medical are working through that.
"Had a quick touch with her as she was being stretchered off, a quick word and encounter, but she seemed in pretty good spirits when she was coming off.
"'Braz' is a pretty strong character and she's full of life, so she'll always look at the positive side of it."
Also an Australian netball player, Brazill was stretchered from the ground in the dying minutes of the third term, administered the strong pain relieving "green whistle" and gave thumbs up to the crowd at Marvel Stadium.
The Pies already lost Ruby Schleicher to an arm injury earlier in the match.
There have already been nine torn ACLs suffered in training, practice games and official AFLW matches since the start of pre-season in November last year.
